The Synthesis And Characterization Of Ferrocenyl Dihydropyrans

Since1951, the studies on the synthesis and property of ferrocene and its derivativeshave attracted many researchers due to their unique electrochemical property and sandwichmolecular structure. Ferrocenyl derivatives are a class of important organometalliccompounds, and widely used in the field of material science, bio-medical chemistry,asymmetric catalysis, liquid crystal materials and electromagnetic field. Of course, thedesign motif and synthesis strategy for ferrocenyl-based architectures play the mostimportant roles in delivering the required properties. Although ferrocenyl derivatives areclassical aromatic compounds, traditional methods for the constructing aromaticcompounds may not work for ferrocene due to its specific geometric and electronicproperties. Furthermore, ferrocenyl fragments are sometimes sensitive to acid and hightemperature. Therefore, developing efficient methods for their synthesis under mildreaction conditions remains to be a challenge.Multicomponent reactions (MCRs) have become a promising tool for synthetic organicchemists due to their advantages of intrinsic atom-economy, simpler procedures, structuraldiversity, energy savings and reduced waste. A literature survey stated that reactions of thesubstituted3,4-dihydropyrans have been rarely explored due perhaps to the difficulty ofpreparation by the multicomponent reactions, and the ferrocenyl dihydropyrans has notbeen reported yet.In this dissertation, we will report our successful endeavor, in which a new class offerrocenyl derivatives,2-ferrocenyl-3,4-dihydropyrans, were synthesized throughthree-component reaction of formaldehyde,1,3-dicarbonyl compound and vinylferrocene,which is rather susceptible to acid and high temperature, in acetonitrile near roomtemperature under catalyst-free conditions. Furthermore, the obtained ferrocenyldihydropyrans can also react readily with indole in the presence of catalytic amount ofalum, providing a ring-opening product in high yield.The components and structures of the novel compounds1-9were characterized bymelting point, elemental analysis, FT-IR, NMR and MS. The molecular and crystalstructures of the compounds3and4were determined by X-ray single crystal diffraction.